Heating furnace control



R. W, TM

HEATING FURNACE CONTROL Filed OCT.. l?. 195C Aug. 9,! 1932,

Patented Aug. 9, 1932 i UNITED s'iaras PATENT orricr.

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This invention relates to improvements in the thermostatic control of furnaces used for heating houses, oilices, shops and other buildings and the like. The invention is of special l value and application in connection with the use of solid fuels such as coal and coke, and in the -burning'of gaseous fuel such a natural and manufactured gas, but it also has certain advantages in the burning of liquid fuels such 10 as oil;

In `conventional practice a thermostat actuated by the temperature in the enclosed space to be heated is arrangedl to initiate, or to accelerate or promote, combustion in the fur- .1I nace when the temperature in this space falls below a predetermined minimum limit and to stop, or to retard or inhibit, combustion in the furnace when theJtemperature in this s ace rises above a predetermined maximum limit.

` 39 While the results so obtained are fairly satisfactory with respect to control of the temligrrature in that part of the enclosed space to heated in which the thermostat is arranged, with'n the limits of the thermostats u used, this p actice disregards several elementsl essential to eicient o ration of the furnace and is subject to the limits of a single thermostat arranged in one part of the enclosed space to be heated. 3 The p resent invention provides an improved thermostat arrangementwhich ha several im ortant advanta The invention includes an improvedgetszhermostat arrangement by which the several factors de termining the temperature in the enclosed space to be heated and the eiliciency of opera, tion of the furnace are correlated to adjust each with respect to the others to secure satisfactory temperature re Vulation and atv the same time to promote e Vciency of operation. The invention also includes an improv thermostat arrangement avoiding many of the limits to which conventional thermostats conventionally arranged are subject.

The invention will be further described in connection with the accompanying drawing which illustrates, diagrammatically and conventionally, an embodiment of the invention. In the drawing Fig. 1 illustrates an embodi- 5 ment of the invention including one particularly advantageous thermostat arr and Fig. 2 illustbres a modified thermostat arrangement em in in certain respects features described ih iy a plication filed September 6, 1930, Serial umher 480,045. It is intended and will be understood that the accompanying drawing is intended merely to illustrate the invention and that it is not to be interpreted in any limiting sense.

The accompanying drawing illustrates a heating furnace 1 which comprises the usual fire-box in which fuel is burned, heat transferring surfaces over which the hot products of combustion from the fire-box pass for the transfer of heat to the heating medium, air, water or steam for example, used in the heating system and a stack flue 2 communieating with a chimney 4 through which the hot gases from the lire-box which have passed over the heat transferring surfaces escape. The motor of a motor driven means for effecting combustion of fuel in the fire-box is shown at 3. The means shown com rise a fan arranged to provide forced draft t rough a grate on which coal or coke, for example, is burned. Instead of such a forced draft fan, an induced draft fan may be positioned in the stack ilue. Or an oil burner, for example, may be arranged, generally with respect to the heating furnace, as shown in the drawl in c nstead of being arranged in the s pace to be heated, as in conventional practice, the thermostat o, which is responsive to the temperature in the enclosed space to be heated is arran in a thermostat chamber 6 appropriate y insulated, thermally, and remotely situated with respect to the enclosed space to be heated, a room 7 in a building for example, which is connected to one or more pilot oried liess, such as pilot orice 8, 'in the enclosed space to be heated so that a flow of air is 'maintained from the enclosed space to be -heated through the orifice 8 and thence u through the chamber 6.

Several important advantages are thus seentu cured, one of the more important of which is the avoidance of any limitation as to the size, which Yin turn is a limitation as to the accuracy and dependability, of the thermostat or temperature responsive means used. Such pilot orifices, moreover, are unobtrusive and readily concealed, maly be located with great freedom, tend themse ves to promote the flow of air necessary to representative indication at the point of location of the mean temperature in the space to be heated, and do not afford an opportunit for casual tampering. In conjunction with electrically controlled systems this thermostat arrangement makes it possible to localize wiring and also malres it possible to eliminate complications 1nvolved in the use of transformers, relays and the like necessary in low voltage control circuits, and since usually a lar eproportion of the assem ly can be comple at the factory, installation costs may be reduced.

In the embodiment illustrated the flow of air through the orice 8 and connection 9 between this'oriiice and the chamber 6 is mamtained by connections 10 and 11 between the chamber 6 and the chimney 4. A fan or blower or the like, as indicated at 12, may be provided to assist in maintainin this iiow if the pressure diiferential provided by the chimney is irregular or msuicient. The connection 9 may be of any material reasonably air-tight'and a poor conductor of heat, rubber or canvas or composite tubin for example. Such tubin ma be easily snaked through floors, wal s an partitions of conventional construction.

The thermostat chamber 6, moreover, may be made to integrate temperatures in a plurality of enclosed spaces to be heated by connection to similar pilot orifices arranged 1n each of them through connections correspending to connection 9 such as 9 and 9" and so on, and the relative weights of the temperatures prevailing in each of such a plurality of spaces with respect to the operation of the thermostat 5 may be proportioned by valves or dampers, as indicated at 13, 13' and 18" for example, in the several connections.

The arrangement so far described, the provision of a thermostat chamber remotely situated with respect to an enclosed 'space or spaces to be heated and connected to one or more pilot orifices opening into the space or spaces with tem rature responsive means adapted to contro 'the heating furnace arranged in this chamber, is of general application in the burning of solid or liquid or gaseous fuels. c

The control s stem illustrated in Fig. 1 comprises, in addition to the thermostat 5 responsive to the tem rature in the enclosed space to be heated, a t ermostat 14 responsive to the temperature of the gases escaping through the stack flue 2. The thermostat 14 is arranged in the thermostat chamber 15 which is connected to the exhaust connection 11 and, by means of connection 16, to a heat exchanger 17 arranged about the stack due 2 :,eracaa so that the temperatur of the gaseous medium flowing through t e chamber 15 reiiects the temperature of the gases escaping through the stack flue 2.

The thermostat 5 is adapted to close the power circuit through the motor 3 through contacts 18 as the temperature in the e'nclosed space to be heated falls and to open the circuit as that temperature rises and the thermostat 14 is adapted to lower the tem erature at which the ower circuit throng the motor 3 is closed rough contacts 18 as the temperature of the gases escaping through the stack Hue 2 rises and to raise the temperature at which the power circuit through the motor3 is closed through the contacts 18 as the temperature of the gases escaping through the stack ue 2 falls.

The temperature in the enclosed space to be heated and the temperature of the waste gases escaping through the stack flue, a significant measure of the eiciency of operation of the furnace, are thus correlated or counter-balanced so that proper weight is .given to each in determining the operation of the combined control system. The two thermostats in the combined control system thus operate conjointly to control the furnace operation with respect to these several factors.

An auxiliary pair of contacts 19 may be provided to maintain the temperature of the gases escaping through the stack Hue 2 above aA redetermined minimumlimit irrespective o the operation of the thermostat 5. A stop 20 may be provided to maintain the temperature of the gases escaping through the staclr flue 2 below a predetermined maximum limit irrespective of the operation of the 'thermostat 5.

With the thermostat arrangement just described, the thermostatic means may be adjusted to provide for operation of the furnace under conditions approximating those of maximum eiciency when the demand for heat, as measured by the temperature in the enclosed space to be heated, is normal yet to rmit operation of the furnace under con itions of increased capacity, though usually of decreased eilciency, during periods when the demand for heat is abnormal.

For example, this thermostat arrangement makes possible the operation of the heating furnace u nder conditions approximating those of maximum efficiency when the temperature of the enclosed space to be heated 1s, for example, within 2- of the predetermined minimum limit et provides for operation of the heating urnace at maximum capacity irrespective of eiciency should the temperature in the enclosed space to be heated for any reason fall say 20 below the predetermined minimum limit. For usual domestic heating purposes, for example, this thermostat arrangement provides than eiciency,

for an ellicient. furna .operation during that part of the day whencethe house is to be maintained at a predetermined temperature yet provides for furnace operation at maximum capacity when the house is to be brought to a predetermined temperature from some substantially lower tem rature, a peri during which capacity 1s more important as when an adjustment of the temperature to which the control system respends is made say evening and morning, manually or by clock mec anism, for the maintenance of a lower temperature during one period of the day and of a hi her temperature during another lperiod o the day. In the embodiment illustrated the pair of contacts .19 further provides for the maintenance of a minimum temperature of the stack gases, a matter of eiliciency and in the burning of solid fuels a matter of safety, irrespective of the temperature in the enclosed space to be heated and the stop imposes a maximum limit, a matter of safety, upon the temperature of the stack gases.

The thermostats 5 and 14 in the embodiment illustrated are of the conventional bellows type. The exact form of the thermostats or temperature responsive means is not .essential to the invention. Appropriate adjustments are provided, as indicated for exam le at 21, 22, 23, 24, and 26.

t will be understood that the relative size, power and travel of the thermostats 5 and 14 and the relative increase or decrease of motion represented b the arrangement of linkages connecting t e thermostats proper with the contacts, stops or other control means are to be proportioned with respect to the particular conditions for which the thermostat is designed. It will also be understood that various other control elements, limitin controls for example, may be incorporate into the system just described without de arting from the invention; limitin contro s operating against a predetermine maximum pressure limit in thed case of steam heating systems for example.

The arrangement just previously described, the combined control system comp'rising correlated temperature responsive means operating conjointly tocontrol the heating furnace with respect to the several factors involved, is of special application in the burning of solid fuels.

Some of the advantages of the invention may be secured if the arrangment of thermostats illustrated in Fig. 2 substituted for that illustrated in Fig. 1. For the purpose of illustration that terminals a and b are indicated as the points of substitution. The same reference characters are used in Fig. 2 as in Fig. l to designate the same or corresponding parts.

. With the arrangement illustrated in Fig.

v2, the thermostat 5 is adapted to close the od the thermostat means of pressure power circuit through the motor 3 through contacts 27 when the temperature in the enclosed space to be heated falls below a predetermined minimum limit and to open this power circuit when this temperature rises above a predetermined maximum ,limit and 14 is adapted to close the power circuit through the motor 3 through contacts 28 when the temperature of the gases esca ing through the stack due 2 falls below a pr etermined minimum limit irrespective of the operation of the thermostat 5.

Having described my invention, I claim:

1. An improved heating control for a furnace connected to a chimney which tends to induce a draft through the furnace comprisin g a thermostat chamber remotel situated with respect to an enclosed space to heated a pilot orifice opening into said space and means including a connection between said oriice and said chamber for maintainin by differential available om the chimnev a ilow of air from said space through said chamber, and temperature responsive means adapted to control said furnace arranged in said chamber.

2. An improved heating control for a furnace connected to a chimney which tends to induce a draft through the furnace comprise ing a thermostat chamber remotely situated with respect to a plurality of enclosed spaces to be heated, a pilot orifice in each of said spaces and means including connections between said orifices and said chamber for maintaining by means of pressure differentiall available from the chimney a flow of air from said spaces through said chamber, and temperature responsive means adapted to control said furnace arranged in said chamber.

3. An improved heating control for a furnace connected to a chimney which tends to induce a draft through the furnace comprising a thermostat chamber remotely situated with respect to a plurality of enclosed spaces to be heated, a pilot orifice in each of said spaces and means including connections between said orilices and said chamber for maintaining by means of pressure di ilerentia-l available from the chimney a How of air from said spaces through said chamber, means for proportioning the liow through said several orifices, and temperature responsive means adapted to control said furnace arranged in said chamber.

4. An improved heating control for a furnace connected to a chimney which tends to induce a draft through the furnace comprisingr a thermostat chamber remotely situated with respect to an enclosed space to be heated1 a pilot orifice opening into said space and means including a connection between said orifice and said chamber and a connection between said chamber and the furnace stack for maintaining by means of pressure differential comprisin available from the chimney a flow of air from said sKace through the chimney.

5. n improved `heating furnace control a pair of thermostat chambers remotely situated with respect to an enclosed space to be heated, a pilot orice opening into said space and means including a comiection between said orifice and one of said chambers for maintaining a flow of air from said space through the first chamber, means for maintaining a flow of a gaseous medium the temperature of which rellects the temperature of the gases escaping through the furnace stack through the other chamber, and thermostatic means adapted conjointly to control said furnace arranged in said chambers.

6. An improved heating furnace control comprising a pair of thermostat chambers remotely situated with respect to an' enclosed space to be heated, a pilot orifice opemng into said space and means including a connection between said orice and one of said chambers for maintaining a flow of air from said Space through this first chamber, means for maintaining a dow of'a gaseous perature of which reects the temperature of the gases escaping throu h the furnace stack through the other cham portioning the flow through said chambers, and thermostatic means adapted conjointly to control said furnace arranged in said chambers. n

7. An improved heating furnace control comprising thermostatic means responsive to the temperature prevailin in the enclosed space to be heate adapte to promote combustion of fuel in said furnace as that temperature falls and to inhibit such combustion as that temperature rises, and thermostatic means responsive to the temperature of the gases escaping through the furnace stack adapted to lower the temperature to which said first-mentioned thermostatic means re sponds 4to promote combustion of fuel in the furnace as the temperature of the stack gases rises and to raise the temperature to which said first-mentioned thermostatic means re sponds to promote combustion of fuel in the urnace as the temperature of the stack gases alla.

8. An improved heating furnace control comprising thermostatic means responsive to the temperature revailin in the enclosed space to be heate adapte to promote combustion of fuel in said furnace as that temperature falls and to inhibit such combustion as that temperature rises, and thermostatic means responsive to the temperature of the gases escaping through the furnace stack adapted to raise the temperature to which said first mentioned thermostatic means responds as the temperature of the stack gases rises and to lower the temperature to which said first-mentioned thermostatic lmeans responds as the temperature of the stack gases medium the temn r, means for proth falls and adapted to maintain the temperatureof the stack gases above a redetermined minimum limit irrespective o the operation of the said first-mentioned thermostatic means. l

9. improved heating furnace control comprising thermostatic means responsive to the temperature revailin in the enclosed space to be -heate adaptedg to promote combustion of fuel in said furnace as that temperature falls and to inhibit such combustion as that temperature rises, and thermostatic means responsive to the temperature of the gases escaping through the furnace stack ada ted to raise the temperature to which sai first-lnentioned thermostatic means re sponds as the temperature of the stack ases rises and to lower the temperature to w ich said first-mentioned thermostatic means re sponds as the temperature of the stack gases falls and adapted to maintain the temperature of the stack gases below a redetermined maximum limit irrespective otp the operation of the said {first-mentioned thermostatic means.

roved heating furnace control comprising t ermostatic means responsive to e temperature' revailin in the enclosed space to be heats adapte to promote combustion of fuel in said furnace as that temperature falls and to inhibit such combustion as that temperature rises, and thermostatic means responsive to the temperature of the gases escaping through the furnace stack adapted to raise the temperature to which said lirst-mentioned thermostatic means re sponds as the temperature of the stack s rises and to lower the temperature to w ich said first-mentioned thermostatic means re sponds as the temperature of the stack gases falls and adapted to maintain the temperature of the stack gases above a predetermined minimum limit and below a redetermined maximum limit irrespective of) the operation of the said first-mentioned thermostatic means.

11. An improved heating furnace control, comprising t ermostatic means responsive to the temperature of the through the furnace stack adapted to promote combustion of fuelin said furnace as the temperature in the stack falls and to inhibit such combustion as the temperature in the stack rises, and thermostatic means responsive to the temperature revailing in an enclosed space to be heated) adapted to raise the temperature to which the thermostatic means responsive to the temperature of the gases escaping through the stack responds to promote combustion of fue] in said furnace as the temperature in the enclosed s ace falls.

12. An improved heating furnace control, comprising a pair of thermostatic mecha nisms, one responsive to the temperature preveiling 1n an enclosed space to be heated, and

gases escaping the other to the temperature of the gases escepin through the furnace stack, each of Bald ermostatic mechanism being adapted at different times to promote combustion of fuel in the furnace and to inhibit such combustion, said thermostatic means bemg so correlated that e chen in the temperature which controls one t ermostetic mechanism causes a. change in the temperature at which v 1 the other thermostatic mechanism is effective to change the rate of combustion of fuel in the furnace.

In testimony whereof I eiix l?? si ature.

RUSSELL S M.

CERTIFICATE or connection. A

man: No. 1,811,093. f i im 9, 19.32.

RUSSELL w. stm

It in hereby certified that error appears in the printed specification-'oi the v above numbered patent requiring correction as follows: Page 4', yline 2. chill 4. for the-word "chimney" read chamber; and thlt the said Lettere Ptentlrifliilld be read with this correction therein that the same may eonioml to thereeordhf' the ease in the Patent Office.

Signed and sealed this 22nd day of November, A. D. i932.

M. lfMoore, i v l f (sul) f f- MM-Cmmifoneropflm the other to the temperature of the gases escepin through the furnace stack, each of Bald ermostatic mechanism being adapted at different times to promote combustion of fuel in the furnace and to inhibit such combustion, said thermostatic means bemg so correlated that e chen in the temperature which controls one t ermostetic mechanism causes a. change in the temperature at which v 1 the other thermostatic mechanism is effective to change the rate of combustion of fuel in the furnace.

In testimony whereof I eiix l?? si ature.

RUSSELL S M.

CERTIFICATE or connection. A

man: No. 1,811,093. f i im 9, 19.32.

RUSSELL w. stm

It in hereby certified that error appears in the printed specification-'oi the v above numbered patent requiring correction as follows: Page 4', yline 2. chill 4. for the-word "chimney" read chamber; and thlt the said Lettere Ptentlrifliilld be read with this correction therein that the same may eonioml to thereeordhf' the ease in the Patent Office.

Signed and sealed this 22nd day of November, A. D. i932.

M. lfMoore, i v l f (sul) f f- MM-Cmmifoneropflm 

